5-methyl-pyridine-2-sulfonic acid [6-methoxy-5-(2-methoxy-phenoxy)-2-pyridin-4-yl-pyrimidin-4-yl]-amide corresponding to the formula
is an inhibitor of endothelin receptors. WO00/52007 describes the preparation of said compound which is crystallized from Me2Cl2.
Own investigations have shown that there exist two distinct crystalline forms, hereinafter referred to as form A and form B, as well as a number of further solvates, in particular the methanol, ethanol, isopropanol, dichloromethane, acetone, methyl ethyl ketone and tetrahydrofuran solvates.
It was further surprisingly found that the thermodynamically stable crystalline form—form B—can be prepared under controlled conditions and that said form B can be prepared with a reliable method in an industrial scale, which is easy to handle and to process in the manufacture and preparation of formulations.